Aluminum alloys



Patented Oct. 31, 1933 UNITED STATES PATENT OFFICE ALUMINUM ALLOYS NoDrawing.

Original application September 21,

1932, Serial No. 634,155. Divided and this application November 645,123

30, 1932. Serial No.

1 claim. (01. 75-21) This invention relates to aluminum base alloyscontaining magnesium. The invention has for its object the improvementof alloys of this class,

by the addition thereto of about 0.05 to 2.0 per cent by weight ofcalcium. The invention is particularly concerned with the specificalloys hereinafter described.

The claim of this application covers certain matter divided from mycopending application Serial No. 634,155 which is, in part, acontinuation of my copending application Serial No. 595,231. Inventionsdisclosed but not claimed herein are claimed in my copendingapplications Serial Nos. 595,231, filed February 25, 1932, 645,- 108 to645,122 inclusive, 645,124, and 645,125, all filed November 30, 1932.

Considerable difiiculty has heretofore been en-- countered in attemptsto commercially produce castings of aluminum base alloys containingsubstantial amounts of magnesium. This difficulty is encountered both inthe making of sand castings and permanent mold or chill-mold castings,although the nature of the diificulty differs somewhat in each case. Inthe case of sand castings there occurs a reaction between the moltenaluminum base alloy containing magnesium and the ordinary sand-moldmaterials, or vapors generated therefrom. There is also a reaction withthe atmosphere. In addition, the magnesium-containing aluminum basealloy does notflow freely through narrow mold sections at ordinarypouring temperatures and, if the pouring temperature be raised, thesolidified alloy is unsound. If the aluminum base alloy contain ingmagnesium be cast in a chill-mold the reaction eflect is minimized tosome extent, but the troubles arising from cold-shuts and mis-runs areaccentuated because of the more rapid chilling of the molten metal. Theconsiderations apply to the aluminum base alloys specifically disclosedherein and particularly to such alloys.

I have discovered that when calcium is added to aluminum base alloys ofthe type and composition herein described, these difliculties are, to aconsiderable extent, eliminated. The calcium should be present inamounts ranging from 0.05 per cent to 2.0 per cent by weight subject tospecific considerations as hereinafter disclosed.

In the melting of aluminum alloys of the compositions herein described,a viscous scum often forms at the surface of the molten metal. Failureof the molten metal to run properly through narrow mold apertures iscaused, in part, by shredsorparticlesotthisscumbelngsuspended in themolten metal and offering a resistance to the free passage of the metalthrough the apertures. Regardless of the cause of this low fluidity,Imhave discovered that the addition to the alloy of'relatively'small'amountsr0239};00 cium, in the preferred range between0.05 to 0.5

per cent, improves the casting characteristics to a very considerableextent and simultaneously effects a reduction of the scum or drosscollecting at or near the surface. In the casting of articles in sandmolds, I prefer to add calcium in amounts less than about 0.5 percentexcept in instances where some reduction of tensile strength or othermechanical or tensile property is immaterial. In amounts of more than0.5 per cent the calcium addition produces the advantages enumeratedherein but has a tendency to lower some of the physical properties ofthe alloys. This effect is not harmful when calcium is present inamounts of about 0.5 per cent or less, but when high strength is not adesideratum the calcium may be used in amounts up to about 2.0 per cent.In intricate permanent mold castings, where casting troubles are veryserious if no calcium be added, the improved physical propertiesobtained coincident with the production of good castings more thanoffset the diminution in properties which might otherwise result fromthe use of the calcium.

I have also discovered that when calcium is added to aluminum basealloys containing magnesium, the amount of gas evolved duringsolidification of the alloys'is considerably reduced. When from about0.05 per cent to 2.0 per cent by weight of calcium is added to thealloys, the amount of gas evolved becomes less marked with increasingcalcium content and the reduction of gas evolution may be so marked thatthe molten metal cools to' the solidification temperature with a smoothmirror-like surface. I prefer to restrict the amount of calcium added to2.0 per cent or less since above this amount the physical properties ofthe alloys may be too seriously affected. If the best physicalproperties are desired with an improved, although not complete, degreeof gas prevention, I keep the calcium content of the alloys between 0.05per cent and about 0.5 per cent.

In the application of the principles of my invention I have determinedthat certain aluminum-base alloys containing magnesium are particularlybenefited thereby. For example, a very useful aluminum base alloy is onecontaining about 2.0 to 9.0 per cent of magnesium and 0.05'per cent to2.0'per cent of calcium, as is also aluminum base alloy containing about2.0- to 15.0. per cent of magnesium, 0.1 to 3.5 per cent of cobalt, and0.05 to 2.0 per cent of calcium to which other elements such as copper,antimony, bismuth, nickel, manganese, and other well known alloyingelements may be added to produce particular properties therein.

Likewise'is the addition of 0.05 to 2.0 per cent of calcium beneficialto those aluminum base alloys which contain'about 2.0 to 15.0 per centof magnesium and 0.05 to 0.4 per cent of at least one of the class ofmetals here defined as antimony and bismuth, such alloys being veryuseful where use at high temperatures is contemplated. Calcium maylikewise be added to improve such alloys when they contain, in additionto magnesium and antimony and/or bismuth, one or more of such alloyingelements as cobalt, copper, nickel, manganese, zinc, etc. which may beadded to modify or produce a specific property in the alloy.

The addition of 0.05 to 2.0 per cent of calcium is very beneficial inthe case of a series of aluminum base alloys which .contain as majoralloying elements about 2.0 to 10.0 percent of magnesium and about 0.2to 5.0 per cent of nickel. For instance, an aluminum base alloycontaining 3.0 to 7.5 per cent of magnesium and 0.2 to 2.0 per cent ofnickel is improved by the addition of 0.05 to 2.0 per cent of calcium asis, likewise, this same alloy when it also contains about" 0.05 17004per cent of one or more of the class of elements composed of antimonyand bismuth. Another excellent aluminum base alloy prepared inaccordance with the principles of my invention is one containing 3.0 to8.0 per cent of magnesium, 0.5 to 4.0 per cent of nickel, 0.5 to 4.0 percent of manganese, and 0.05 to 2.0 per cent of calcium, which alloy mayalso be improved, particularly for application at high temperatures, bythe addition of 0.5 to 0.4 per cent of at least one of the class ofelements composed of antimony and bismuth.

The principles of my invention find particular application in the caseof aluminum base alloys containing magnesium, nickel, and chromium, andaluminum base alloys containing magnesium, nickel, and copper, aswell asthose alloys containing magnesium, nickel, and cobalt. Examples may begiven of aluminum base alloys containing 2.0 to 10.0 per cent ofmagnesium,

. 0.2 to 5.0 per cent of nickel, 0.5 to 3.5 per cent of chromium, and0.05 to 2.0 per cent of calcium. An aluminum base alloy containing 3.0to 8.0 per cent of magnesium, 0.5 to 3.5 per cent of nickel,

' 0.5 to 3.5 per cent of chromium, and 0.05 to 2.0

per cent of calcium has excellent casting properties and the hightemperature properties of.

this alloy can be favorably affected by the addition of 0.05 to 0.4 percent of at least one of a class of elements composed of bismuth andantimony. Examples may be given of aluminum base alloy containing 2.0 to10.0 per cent of magnesium, 0.2 to 5.0 per cent of nickel, 1.0 to 6.0

per cent of copper, and 0.05 to 2.0 per cent of calcium. An excellentalloy of this type is one containing 3.0 to 8.0 per cent of magnesium,0.5 to 5.0 per cent of nickel, 1.0 to 6.0 per cent of copper, and 0.05to2.0 per cent of calcium with or without 0.05 to 0.4 per cent of atleast one of the class of elements composed of antimony and bismuth andwith or without the further addition of 0.5 to 3.5 per cent of at leastone of a class of elements composed of cobalt and chromium, and with orwithout the further addition of 0.1 to 1.0 per cent of at least one of aclass of elements composed of tungsten, vanadium, molybdenum, titanium,and zirconium.

Other excellent alloys are those aluminum base alloys containing about2.0 to 10.0 per cent magnesium, 0.2 to 5.0 per cent nickel, 0.1 to 3.5per cent cobalt, and 0.05 to 2.0 per cent of calcium. A particularexample of this class of alloys, which may also contain withconsiderable advantage 0.05 to 0.4 per cent of a class of elementscomposed of antimony and bismuth, is the aluminum base alloy containing3.0 to 8.0 per cent magnesium, 0.5 to 4.0 per cent nickel,

-0.1 to 3.0 per cent cobalt, and 0.05 to 2.0 per cent calcium.

Among other magnesium-containing aluminum base alloys which I have foundto be particularly benefited by the presence of calcium are numbered thealuminum base alloys containing 3.0 to 8.0 per cent of magnesium, 1.0 to6.0 per cent of copper, 0.5 to 3.5 per cent of chromium, and 0.05 to 2.0per cent of calcium, with or without the addition of 0.05 to 0.4 percent of at least one of a class of metals composed of antimony andbismuth and with or without the addition of other alloying elements.

The alloys herein described may be produced by the usual methods ofalloying metals. The calcium is preferably added to the molten alloy bythrusting the calcium beneath the surface with tongs or other suitableinstrument. The aluminum used in preparing the alloys may be .pure or itmay contain the impurities found in commercial grades of this metal.Ordinarily a good commercial grade of virgin aluminum will giveexcellent results and is preferable.

Having thus explained and described my invention, I claim:

A metallic alloy consisting of about 2 to 15 per cent by weight ofmagnesium, 0.1 to 3.5 per cent by weight of cobalt, 0.05 to 0.4 per centby weight of at least one of the class of elements I composed ofantimony and bismuth, and 0.05 to 2.0 per cent by weight of calcium, thebalance being aluminum. 1

ROBERT T. WOOD.

CERTIFICATE OF CORRECTION.

Patent No. 1,932,869. October 31, 1933.

' ROBERT T. WOOD.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,line 42, for "0.5" read 0.05; and that the said Letters Patent should beread with this correction therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 5th day of December, A. D. 1933.

F. M. Hopkins I Acting Commissioner of Patents-

